BRIEF DESCRIPTION OF THE PRIOR ART
A number of types of dental floss holding devices have previously been provided which retain a strand of dental floss taut in the form of some type of bight or span in order to permit the device to be used to force the floss between the teeth and allow it to be worked back and forth in the cleaning operation.
In U.S. Pat. No. 3,289,681, issued to Chambers, a floss holding compartment or housing is provided on a dental floss cleaning device. This compartment has a hinged lid which permits the floss to be placed in a reservoir cavity. The floss is drawn from this location to a flossing span. After the floss is positioned to extend in a bight or span, it is clamped in this position by the use of ribbed protuberances which clamp on the floss.
A flossing span extended between a pair of posts or spaced structures is shown in Segerblom U.S. Pat. No. 2,756,758. The dental floss span is extended across from a leg of the device to a handle, and there is no space between such leg and handle to accommodate the lip and front teeth of the user of the device at the time when it is being used, and this makes it difficult to reach and clean the back teeth. In the Segerblom patent, no protective shield or canopy is provided which will protect the dentist, hygenist or technician against ricocheting or spattering material pried loose during the cleaning of the teeth.
Another U.S. patent having to do with devices for utilizing dental floss for cleaning teeth is Sonnenberg U.S. Pat. No. 2,052,520.
In U.S. Pat. No. 4,495,957, some finger actuated clamping levers are provided for holding the floss strand taut.
Yet another patent which has to do with dental floss holding and teeth cleaning devices include Wofford U.S. Pat. No. 4,660,584 which leads floss from a roll carried within a housing through an elongated shaft or arm, around an arcuate end portion and back through a bight or span.
Another dental floss holding tool is that which is illustrated in Bowden U.S. Pat. No. 4,655,234. The Bowden patent feeds the floss from a roll carried in a generally cylindrical housing out through a hollow shaft, around through an arcuate end portion and back to a post where the floss is stopped off. There is no space provided for the accommodation of the lip or front teeth of the user at a time when the back teeth are being cleaned, and the Bowden patent does not show any type of shield or protective canopy for preventing debris and saliva from leaving the mouth.
Other types of dental floss devices are shown in Schiff U.S. Pat. No. DES.-251,075, Lewis U.S. Pat. No. 3,094,996, Shepard 2,163,500, Bowling et al 1,623,231 and Ecauburt 1,287,926.